Radarcape:NTP

Required Linux/Unix skills to execute this task: Advanced

NTP

Basics

A Radarcape or Airsquitter in its regular operation comes with a built in GPS module, so nothing is easier than using that as a time source, too. Fallback options are NTP to given servers.

NTP client

The fallback NTP server for system time - but not MLAT timestamps - can be configured in Settings -> Network.

NTP stratum 1 server

As it comes out of the box, Radarcape and Airsquitter can be used as Stratum 1 NTP source. Configure any client to use it as NTP server.

Local Time Synchronisation via NTP

In order to have correct time on Angstrom based Radarcapes, due to a hardware probelm in our cape board, a special kernel is required.

The Radarcape's hardware design will support true NTP using the GPS. Both, the Trimble serial data stream as well as the 1PPS, are available on the Beaglebone. However due to time constraints using those in order to create a Stratum 1 NTP server was not yet implemented.

Important Note: Timestamping of the Mode-AC/Mode-S raw data frames is _not_ done using the system time which is described here. All received frames are directly time stamped in the FPGA without any interaction of the local CPU or operating system. However, the __date__ in Port 30003 messages is always the Linux system date. The __timestamp__ instead is a GPS timestamp when the config is set to GPS timestamps and system time when the Radarcape operates in legacy 12MHz timstamp mode.